Nucleotide sequence of the transposable element IS15

We have determined the complete nucleotide sequence of the right (R) copy of the insertion sequence IS15 which flanks, in direct orientation, the composite transposon Tn1525. IS15-R, which is capable of independent transposition, is 1648 bp long and has short (14 bp) perfect inverted repeats at its termini. Analysis of the nucleotide sequence indicates that IS15-R results from the transposition, in direct orientation, of a smaller (820 bp long) IS, designated IS15-Δ, into itself. This integration event is accompanied by the duplication of 8 bp in the target DNA. IS15-Δ possesses two large overlapping open reading frames (ORF) located on opposite strands. Because of this particular structure, IS15 possesses four large ORFs which, due to the integration event, exhibit some differences with those of the parental 1S15-Δ.     

Phenotypic changes in hydrogen evolving chemostat cultures of Rhodopseudomonas capsulata

Abstract Spontaneous nitrogenase-negative (Nif⁻ mutants of Rhodopseudomonas capsulata were observed to accumulate with time in ammonium- or glutamate-limited chemostat cultures.
Nif⁻ mutants were characterized by their inability to grow under N₂ and to reduce acetylene or produce hydrogen gas when grown on glutamate. They lacked the nitrogenase structural proteins as evidenced by immunological techniques. On the other hand, no significant differences were found in the pathways of ammonia assimilation between the Nif⁻ mutants and the wild-type strain. The Nif⁻ mutants seem to result from a mutation in a regulatory gene.     

Analysis of nuclear sugar-binding components in undifferentiated and in vitro differentiated human promyelocytic leukemia cells (HL60)

The nuclear sugar-binding components (i.e., lectinlike molecules) were analyzed using isolated and membrane-depleted nuclei after incubation in the presence of fluorescein-labeled neoglycoproteins. This analysis was performed before and during the in vitro differentiation of HL60 cells into monocytes by PMA treatment and into granulocytes by DMSO treatment. The nucleoli of undifferentiated and differentiated HL60 cells were not labeled, unlike the nucleoli of other mammalian cells studied so far. This peculiarity allowed us to quantitatively analyze by flow cytometry the changes in the lectin activity associated with the extranucleolar territories enriched in ribonucleoprotein complexes. The neoglycoprotein binding was found to be significantly lower in differentiated than in undifferentiated cells. The decrease in neoglycoprotein binding was observed within the first 24 h of DMSO or PMA treatment, just before the arrest of DNA synthesis. Taking into account that the granulocytic differentiation required 72 h of chemical treatment, the extra-nucleolar lectins might be involved in modulation of the DNA synthesis rather than in phenotypic differentiation. These data are discussed in an attempt to reconcile the association of lectins with RNP complexes and their possible involvement in modulation of HL60 cell proliferation.     

The inhibition of human neutrophil elastase and cathepsin G by peptidyl 1,2-dicarbonyl derivatives

Neutrophil elastase and cathepsin G are serine proteases that can damage connective tissue and trigger other pathological reactions. Compounds containing a peptide sequence to impart specificity and bearing an alpha-dicarbonyl unit (alpha-diketone or alpha-keto ester) at the carboxy terminus are potent inhibitors of the neutrophil serine proteases (human neutrophil elastase: R-Val-COCH3, Ki = 0.017 microM; R-Val-COOCH3, Ki = 0.002 microM; human neutrophil cathepsin G: R-Phe-COCH3, Ki = 0.8 microM; R-Phe-COOCH3, Ki = 0.44 microM; R = N-(4-[(4-chlorophenyl)sulfonylaminocarbonyl]phenylcarbonyl)+ ++ValylProlyl).     

Fungal Catabolism of Crown Gall Opines

This study was conducted to determine the capacities of 37 fungi to utilize various crown gall opines as their sole carbon and nitrogen source. One strain of Fusarium solani, two of Cylindrocarpon destructans, and six of Cylindrocarpon heteronema catabolized octopine, mannopine, octopinic acid, succinamopine, or a combination of these opines. One C. heteronema and one Fusarium dimerum strain grew only on succinamopine. None of the fungal isolates had the ability to grow on nopaline. The catabolism of opines by fungi was confirmed by the disappearance of the opine from the growth medium and by an increase in final mycelial dry weight with rising initial concentration of test substrate. This study thus shows that the catabolism of opines is not restricted to bacteria.     

Specificity of Octopine Uptake by Rhizobium and Pseudomonas Strains

The octopine-utilizing strain Agrobacterium tumefaciens B6S3 and three nonagrobacteria which had the capacity to utilize this opine were compared for octopine uptake. The characteristics of uptake by Rhizobium meliloti A3 and strain B6S3 were similar. In both bacteria, uptake activity was inducible by octopine and by the related opine octopinic acid, and competition assays showed that these two opine substrates were accepted by the same uptake system with an equivalent affinity. Cells of Pseudomonas putida 203 accumulated octopine against a concentration gradient, and this activity was induced specifically by octopine. While strain 203 did not utilize octopinic acid, a spontaneous mutant with a combined capacity for octopine and octopinic acid utilization was obtained. Both opines induced octopine uptake by this mutant, but octopinic acid was not a substrate for the induced system. Thus, the Pseudomonas uptake system exhibited a different specificity for octopine than the corresponding Agrobacterium system. The nonfluorescent pseudomonad GU187j, which utilized the three related opines octopine, octopinic acid, and nopaline, was constitutive for octopine uptake. Strain GU187j possessed a system which accepted these three opines, but not arginine or ornithine, with a similar affinity.     

Identification on I-Ak molecules of a functional site recognized by proliferating T-lymphocytes

The inhibitory capacity of 17 monoclonal antibodies (m.Ab.) specific for the products of the I-A ^k subregion was evaluated in proliferative responses of B10.BR T-lymphocytes to GAT, Keyhole limpet hemocyanin, and ovalbumin. Considered in isolation, each m.Ab. mediated inhibitory effects of comparable magnitude on these three different proliferative responses. On the other hand, clear differences were observed when the magnitude of the inhibitory effects was compared from one m.Ab. to another. The m.Ab. were consequently classified as strong or moderate-to-weak inhibitors of T-cell proliferative responses. Evidence was simultaneously gained indicating the following: (a) the determinants recognized by different m.Ab. were expressed on the same molecules; (b) the differences in affinity of the m.Ab. for I-A^k positive cells did not explain their differences in inhibitory capacities; (c) conversely, the inhibitory capacity of each m.Ab. followed its ability to inhibit the cell surface fixation of Ia.17-specific 10-2.16 m.Ab.; (d) the strong inhibitory capacity of some m.Ab. was not related to a special ability to modulate cell surface Ia molecules. These results suggest that antigen recognition by T lymphocytes is preferentially restricted by a functional site of the I-A^k molecules related to the Ia.17 and Ia.1 specificities.Abbreviations EDTA Ethylenediamine-tetraacetic acid disodium salt - EHAA Eagle's Hanks' amino acids medium - FCS fetal calf serum - in polypeptide G is glutamate, A, alanine, T, tyrosine - HEPES N-2-hydroxy-piperazine-N-2-ethane sulfonic acid - kd dissociation rate constant - KLH Keyhole limpet hemocyanin - LPS lipopolysaccharide - m.Ab. monoclonal antibodies - NP-40 nonidet P-40 - PBS phosphate buffered saline - PBS-BSA PBS supplemented with 1% bovine serum albumin - PBS-BSA-NP-40 PBS-BSA supplemented with 0.5% NP-40 - RT room temperature - SEM standard error of the mean - s.c. spleen cells     

Les ostracodes neogenes du bassin de Savigne-sur-Lathan(Faluns de Touraine) I. Biostratigraphie et paleoecologie

The Neogen formations from the basin of Savigné-su-Lathan (Indre-et-Loire) have yielded 53 species of ostracods.The connections with the best known fauna from the Aquitaine basin and the Rhône basin are discussed.